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Full text of "A History of the Personal Computer"

Chapter 7 Other Software in the 1970' s 

7.1... Operating Systems 

Prior to the introduction of disk drives, software 
was developed to facilitate the loading or "booting" at 
startup. An example of this is the Motorola mini 
operating system for automatic loading called "Mikbug." 

IBM developed the floppy disk drive in 1971 and 
the hard disk drive in 1973. Shugart Associates released 
their 8-inch floppy disk drive in 1973. With the 
availability of disk drives, many manufacturers released 
their own operating systems. However, the dominant 
system was CP/M from Digital Research. 

Digital Research 

Gary A. Kildall received a Ph.D., in computer 
science from the University of Washington, founded 
Microcomputer Applications Associates (MAA) and became a 
professor at the Naval Postgraduate School in California 
in 1972 . MAA was the predecessor to the founding of 
Intergalactic Digital Research by Kildall and his wife 
Dorothy McEwen, in 197 6. The company name changed to 
Digital Research, Inc., in 1979. 

In 1972, Kildall purchased an Intel 4004 
microprocessor and developed emulator and assembler 
programs for it on an IBM System/360 computer at the 
naval school. While continuing to teach at the naval 
school, Kildall' s MAA provided consulting services to 
Intel. This resulted in the development of an emulator 
for the Intel 8008 microprocessor to run on Intel's DEC 
PDP-10 time sharing system. Kildall also developed a new 
systems programming language called PL/M (Programming 
Language for Microcomputers) that was released in 1973. 
Around this time MAA made a proposal to Intel to develop 
a disk operating system for the 8000 series 
microprocessors . 

Intel rejected the proposed operating system. 
However, Kildall continued working on the program and 
named the new operating system Control Program for 



7/1 



7/2 Part II 1970's-TheAltair/Appleera 

Microprocessors (CP/M) . Initially, it would form the 
basis for the resident programming of PL/M for 8080- 
based computers with 16K bytes of main memory and 
Shugart' s new disk drive. This reguired the design of a 
disk controller and the assistance of a friend John 
Torode to get it working. The operating system had 
features such as commands and file naming conventions 
similar to those used on the DEC PDP-10 system. CP/M 
included a single-user file system, and used recoverable 
directory information to determine storage allocation, 
rather than a traditional linked-list organization. MAA 
completed CP/M in 1974 and retailed the program for $70. 
It soon became successful as the dominant 8-bit 
operating system for microcomputers using the Intel 8000 
and Zilog Z-80 series of microprocessors. 

In the mid 1970' s after several implementations on 
computer systems with different hardware interfaces, the 
CP/M software was restructured. CP/M was decomposed into 
two parts : an invariant part that was written in PL/M 
and a small variant part was written in assembly 
language. This small variant module for interfacing to 
various hardware platforms became known as the Basic 
Input/Output System (BIOS) . Computer suppliers and end 
users could now create their own physical input/output 
drivers for CP/M. 

In late 1979, Digital released an enhanced Version 
2.0 of CP/M that sold for $150. The program had been 
completely redesigned to support floppy disk drives and 
high-capacity Winchester disk drives. All disk 
parameters were moved from the invariant part to a table 
driven concept in the variant module. 

Kildall also developed other programs for use with 
CP/M. Some of those were an assembly language, text 
editor and various utilities. Digital Research also 
developed a multi-terminal operating system called MP/M 
(Multi-Programming Monitor) . It provided real-time 
processing with multiprogramming and multi-terminal 
features . The program was compatible with CP/M and sold 
for $300. 



Other Software m the 1 970 ' s 7/3 

Apple Computer 

DOS (Disk Operating System) Version 3.1 was the 
operating system released with the Apple Disk II drive 
in June 1978. The disk had 35 tracks with thirteen 256 
byte sectors on each track for a total storage capacity 
of 113K bytes . Earlier versions were not completely 
functional and therefore not released. Apple released a 
more stable version, DOS 3.2 in mid-1979. 

DOS 3.3 evolved from the release of Apple Pascal 
programming language in 1979. This release changed the 
35 track disk format to sixteen 256 byte sectors with a 
total disk storage capacity of 143K bytes. Apple 
developed a utility called Boot 13 to boot the 13- 
sector-per-track disks. 

Other Operating Systems 

Bill Levy developed PT-DOS for Process Technology 
around 1976/77. Radio Shack released TRSDOS for the TRS- 
80 Mini Disk System in the late 1970' s. It was not 
compatible with CP/M. 

7.2 ... Programming Languages 

BASIC 

A history of the BASIC programming language is 
provided by Thomas E. Kurtz in History of Programming 
Languages 36], pp. 515-549 and by John G. Kemeny and 
Thomas E. Kurtz in Back to BASIC [115], pp. 1-23. A time 
chart depicting the evolution of BASIC is provided by 
Russ Lockwood in a periodical article entitled The 
Genealogy of BASIC [397] . Bill Gates of Microsoft has 
provided an interesting history of BASIC in a periodical 
article entitled The 25th Birthday of BASIC [394] . 
Reference Section 2.2 for the initial development of 
BASIC and Chapter 6 for the Microsoft development of 
BASIC interpreters for the Altair and other 
microcomputers . 

Dartmouth College made a significant upgrade to 
their BASIC compiler with the release of version six in 
September 1971. In 1974, the American National Standards 
Institute (ANSI) formed a committee to develop standards 



7/4 Part II 1970's-TheAltair/Appleera 

for the BASIC programming language. This resulted in the 
release of a standard for Minimal BASIC in 1976 and its 
official approval in 1978. Work then proceeded on a 
standard for a "full" BASIC. Dartmouth released version 
seven of its BASIC compiler in 1979. 

Various hardware manufacturers such as Apple 
Computer, Digital Group, IBM, PolyMorphic Systems and 
Processor Technology developed BASIC languages for their 
own computers. However, Tiny BASIC and the following are 
some of the more significant releases. 

Dennis Allison who was a member of the computer 
science faculty at Stanford University developed Tiny 
BASIC. The initial version of Tiny BASIC developed by 
Allison was a simplified BASIC oriented to younger 
programmers. The program reguired less than 4K bytes of 
memory. The PCC Newsletter and the initial issue of Dr. 
Dobb ' s Journal of Computer Calisthenics and Orthodontia 
in January 1976 provided a detailed description of an 
extended version of the software. Other programmers such 
as Tom Pittman and Li-Chen Wang developed and 
distributed variations of the program for different 
computers [393] . 

Robert Uiterwyk developed SwTPC BASIC for the 
SwTPC 68 00 microcomputer in 1975. SwTPC provided low- 
cost BASIC programs at $1 per kilobyte. A 4K BASIC 
interpreter cost $4, 8K $8 and 12K $12. 

Gordon E. Eubanks developed E-BASIC while working 
on a masters degree in computer science at the Naval 
Postgraduate School in California. Eubanks was 
associated with Gary Kildall and E-BASIC became widely 
used with the CP/M operating system. Gordon Eubanks, 
associates Alan Cooper and Keith Parsons developed C- 
BASIC and founded Compiler Systems, Inc., to market the 
software. Eubanks subseguently sold the Compiler Systems 
company to Digital Research and became one of Digital's 
vice presidents. C-BASIC was a pseudocompiled language 
developed in 1977 for IMSAI and was included with the 
CP/M operating system in 1979. 

Radio Shack released Level-I BASIC with the TRS-80 
Model I computer in August 1977. Steven Leininger 
developed the interpreter by adapting it from Tiny 
BASIC. Radio Shack released Level II BASIC developed by 



Other Software m the 1 970 ' s 7/5 

Microsoft for business and advance applications in 1978 
and an enhanced Level III version in 1979. 

c 

Dennis M. Ritchie created the C language at AT&T's 
Bell Laboratories in 1972 . The language was designed to 
be portable, fast and compact. The UNIX operating system 
was later reprogrammed using the C language. 

FORTRAN 

Reference Section 1.4 for the initial development 
of FORTRAN. Microsoft developed a FORTRAN-80 compiler 
for the Intel 8080 microprocessor. They announced the 
program in April 1977 and sold it for $500. 

Pascal 

Niklaus Wirth developed the Pascal language at the 
ETH (Eidgenossische Technische Hochschule) in Zurich 
Switzerland. Pascal evolved from the ALGOL 60 
programming language. The main development principals 
were to provide a language suitable for structured 
programming and teaching. Wirth drafted a preliminary 
version in 1968 and the first compiler became 
operational in 1970. 

Kenneth L. Bowles directed the development of UCSD 
Pascal at the University of California in San Diego. 
UCSD released the program to users in August 1977 as a 
complete interactive system for microcomputers and 
minicomputers. It was initially released for Digital 
Equipment Corporation (DEC) LSI-11 or other PDP-11 
processors, 8080 and Z80 microprocessors. The software 
system cost $200. Bill Atkinson of Apple Computer, 
adapted the UCSD Pascal for the Apple II computer in 
1979. 



7/6 Part II 1970's-TheAltair/Appleera 

Other Languages 

Gary Kildall of Digital Research, developed PL/M 
(Programming Language for Microcomputers) for Intel in 
1972 . PL/M was a system programming language that 
developed to provide a simpler alternative to assembly 
language for the Intel 8000 series of 8-bit 
microprocessors. It was a refinement of the Stanford 
University XPL compiler writing language with elements 
from Burroughs Corporation's ALGOL and IBM's PL/I. Intel 
marketed the program for the 8000 series of 
microprocessors in 1973. 

BCPL and MESA were systems programming languages 
developed at the Xerox PARC (Palo Alto Research Center) 
for the Alto personal computer in the early 1970 ' s. 

Alan Kay developed Smalltalk at the Learning 
Research Group (LRG) of Xerox PARC in 1972. It was the 
software part of the Dynabook concept and was created 
for the Alto computer. It is one of the first object- 
oriented languages and used interactive graphical 
concepts to create a user friendly environment. 

7.3 ... Word Processors 

Bravo was a word processing program developed by 
Butler Lampson and Charles Simonyi for the Xerox Alto 
personal computer in the early 1970' s. It was one of the 
earliest word processors to feature What-You-See-Is- 
What-You-Get (WYSIWYG) text display on the terminal 
screen. Between 1976 and 1978 improvements were 
incorporated by Simonyi in a new version of the word 
processor called BravoX. During this time Tim Mott and 
Larry Tesler developed a text editor called Gypsy that 
included a new cut-and-paste feature. 

The Electric Pencil evolved from a public domain 
software package called Software Package One (SP-1) . The 
package was distributed by the Southern California 
Computer Society (SCCS) in the fall of 1975. Michael 
Shrayer improved the editor portion of the package and 
called it Extended Software Package 1 (ESP-1) . A further 
upgrade of ESP-1 was called Executer. ESP-1 and Executer 
were the basis for the first word processor for a 



Other Software m the 1 970 ' s 7/7 

microcomputer. Shrayer named it "The Electric Pencil" 
and it became available in December 1976. The first 
version was written for the MITS Altair microcomputer. 
Shrayer founded the Michael Shrayer Software company and 
other versions of the program were developed for various 
microcomputers. An improved version, The Electric Pencil 
II was announced in early 1978 . 

Seymour Rubinstein was the director of marketing 
for IMSAI when he left to start his own company, 
MicroPro International Corporation in late 1978 . He 
hired Bob Barnaby, a programmer who had also worked at 
IMSAI and created a program called NED (New Editor) . 
Barnaby extended this program into a full-scale word 
processor for microcomputers. Barnaby developed two 
programs, a video text editor named Word-Master and a 
sort /merge program named Super-Sort. MicroPro released 
Word-Master at a price of $150 in August 1978 and then 
an improved version named Word-Star at a price of $495 
in June 1979. Word-Star was a success and became a 
dominant word processor used on early CP/M 
microcomputers . 

Apple Writer was created for the Apple II computer 
by Paul Lutus , at a mountain cabin in the wilderness of 
Oregon in 1978. Lutus sold the program to Apple Computer 
for a flat fee of $7,500. Apple Computer released the 
program that sold for $75 in 1979. It featured automatic 
search and replacement of words or phrases, 
justification of text and uppercase and lowercase type. 

John Draper developed EasyWriter for the Apple II 
computer in 1978 . Shortly after, Draper met Bill Baker 
of Information Unlimited Software (IUS) at the third 
West Coast Computer Faire in the spring of 1979. This 
meeting resulted in an agreement being reached for IUS 
to market the program. 

Magic Wand was introduced as an easy-to-use word 
processor in late 1979 by Small Business Applications, 
Inc . 



7/8 Part II 1970's-TheAltair/Appleera 
7.4 ... Spreadsheets 

Daniel S . Bricklin conceived the concept for a 
spreadsheet during his studies for an MBA at the Harvard 
Business School in the spring of 1978 . Bricklin already 
had a degree in electrical and computer science from 
MIT. He had also been a software engineer at Digital 
Eguipment Corporation (DEC) . The impetus for this 
concept was the desire to find a way of utilizing a 
computer to facilitate the financial analysis of varied 
business situations . A prototype of the program was 
written in BASIC and called Calculedger, a combination 
of calculator and ledger. 

It was at MIT that Bricklin had become friends 
with Robert Frankston who would co-develop the software 
for the spreadsheet program. Frankston had done some 
programming for Daniel Fylstra of Personal Software, who 
loaned Bricklin and Frankston an Apple II computer to 
develop the software. 

Bricklin and Frankston formed their own company 
called Software Arts, Inc., in January 1979 to complete 
the development of the spreadsheet software. The program 
was now called VisiCalc, that is an acronym for Visible 
Calculator. Bricklin developed many of the concepts, 
data structures, documentation and specifications. 
Frankston did most of the program coding using assembler 
language and macros. Assembler was used to improve the 
speed and to allow the program to run on a 2 4K byte 
Apple II computer, 32K bytes with a disk. The limited 
memory restricted the spreadsheet to 63 columns by 254 
rows and reduced the number of features incorporated. 
Recalculation was limited to across rows or down 
columns, column widths could be varied, but had to be 
the same and text could not span columns . 

Fylstra offered to sell the program to Apple 
Computer in January 1979 for $1 million. However Steven 
Jobs and Mike Markkula rejected the offer. Bill Gates of 
Microsoft is also reported to have rejected an offer to 
purchase the program. However, subseguently Arthur Rock 
and Venrock Associates assisted in financing Personal 
Software and the new program. 



Other Software m the 1 970 ' s 7/9 

Software Arts signed an agreement with Fylstra of 
Personal Software, Inc., to market VisiCalc in April 
1979. VisiCalc was introduced at the West Coast Computer 
Faire in May, demonstrated at the National Computer 
Conference in June, advertised in the September issue of 
Byte (page 51) and released in October for the Apple II 
computer. VisiCalc was priced at $99.50 then guickly 
increased to $150 after sales increased dramatically. 
One limitation was that it could not run on the CP/M 
operating system, however it was an instant success. 
The term "killer application" has been credited to the 
success of VisiCalc. It also became a significant factor 
in helping to sell Apple II computers. 

7.5 ... Databases 

Lyall Morill developed a simple database program 
for microcomputers called WHATSIT? in 1977. WHATSIT? is 
an acronym for "Wow! How' d All That Stuff get In There?" 
Morill improved WHATSIT? and Information Unlimited 
Software (IUS) introduced the program at the second West 
Coast Computer Faire in the spring of 1978 . Bill Baker 
had previously founded IUS while attending college. 

C. Wayne Ratliff was an engineer who adapted a 
NASA Jet Propulsion Laboratory mainframe database to his 
IMSAI 8 08 microcomputer in his spare time. On 
completion of the software in August 1979, he named it 
Vulcan. The software was marketed by Software 
Consultation Design and Production (SCDP) company and 
advertised in the Byte magazine at a price of $490 
without success. The software was subseguently marketed 
by Ashton-Tate who changed the name to dBASE II in 1981. 

Other early database programs were Condor, FMS 80 
and Selector. 



7/10 Part II 1970's-TheAltair/Appleera 
7.6 ... Miscellaneous 

Games 

Various games had been developed for use on larger 
computers in the 1950' s and 1960's as described in 
Sections 1.4 and 2.6. Then in the early 1970's video 
games that used dedicated processors were introduced and 
became very popular. Most of these video games used high 
resolution graphics and sound effects that would 
subseguently be implemented on more powerful 
microcomputers . 

Nolan K. Bushnell developed the first commercial 
video game called Computer Space in 1970. It evolved 
from his interest in games and his previous exposure to 
the Space Wars game at the University of Utah. Bushnell 
subseguently founded Atari Corporation (see Section 
4.6) . This led to Stephen Wozniak developing an Apple 
Computer version of a game called Breakout that he and 
Steven Jobs had worked on for Atari. Also released at 
Apple Computer was a program called Lunar Lander 
developed by Bob Bishop. Bill Budge also developed a 
number of game programs, such as Penny Arcade, that he 
sold to Apple Computer in 1979. 

In the early 1970' s, Will Crowther developed a 
non-graphic fantasy game that was set in a cavern world 
with hidden treasure and challenging features such as 
dragons, flying horses and trolls. Crowther released the 
game on the ARPANET. The program was then refined by Don 
Woods and became known as the Adventure game. It became 
highly popular and formed the basis for personal 
computer Adventure games by Adventureland International 
and Microsoft. 

Adventure Land was one of the earliest text 
adventure games for personal computers. Scott Adams 
developed the program for the Radio Shack TRS-80 
computer in 1978 . Adventure Land reguired a player to 
search through a magic realm that had wild animals, 
perils and mysteries to locate treasures . Adams founded 
Adventure International in 1978 to produce, be a 
distributor and publisher of other computer games . The 
game was adapted for the Apple II and other games such 



Other Software m the 1 970 ' s 7/11 

as Laser Ball, Fire Copter and Pirate Adventure 
followed . 

Peter R. Jennings developed Microchess initially, 
for the MOS Technology KIM-1 microcomputer in 197 6. 
Jennings sold the source code for $15. Shortly after, 
Daniel Fylstra and Jennings founded Personal Software, 
Inc. to market Microchess and other game programs. 

Another chess playing program was SARGON, that was 
released around 1978. It was developed by Dan and Kathe 
Spracklen. 

Toru Iwatani designed the Pac-Man game at a 
Japanese company called Namco Limited. It was first 
introduced in Japan in the late 1970 ' s. Atari licensed 
the rights for Pac-Man and it became very successful in 
North America. 

Other Software 

Radio Shack issued a variety of software in the 
late 1970' s for their TRS-80 systems. Some of the 
programs were: General Ledger, Inventory Control System, 
Real Estate, Statistical Analysis and various computer 
games. The programs were provided on cassettes and 5- 
inch floppy disks. 

Stephen Wozniak developed SWEET16 in 1977 as an 
interpreter program that was contained in the initial 
Apple II ROM memory chip. Wozniak called it a 16-bit 
"metaprocessor " [402] . It was used to manipulate 16-bit 
pointer data and its arithmetic on the 8-bit Apple II 
computer . 

Mitchell Kapor developed Tiny Troll in 1978/79 
with help from Eric Rosenfeld of MIT. The program 
displayed line charts, multiple regressions, statistical 
analysis information and had a text editor. The software 
formed the basis for the later development of VisiPlot 
and VisiTrend programs . 



7/12 Part II 1970's-TheAltair/Appleera 

Conclusion 

In the 1970' s, software had developed in 
conjunction with personal computer technology. Initially 
it had focused on programming languages such as BASIC, 
and operating systems such as CP/M to support disk drive 
technology. However in the late 1970' s a change in user 
orientation from the technical enthusiast to the mass 
market consumer occurred. This was supported by the 
release of application software such as the VisiCalc 
spreadsheet .